661260590020 has 24 divisors (see below), whose sum is σ = 1390481679384. Its totient is φ = 264154818816.

The previous prime is 661260589999. The next prime is 661260590033. The reversal of 661260590020 is 20095062166.

It can be written as a sum of positive squares in 4 ways, for example, as 53247408516 + 608013181504 = 230754^2 + 779752^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21823057 + ... + 21853336.

It is an arithmetic number, because the mean of its divisors is an integer number (57936736641).

Almost surely, 2^661260590020 is an apocalyptic number.

It is an amenable number.

661260590020 is an abundant number, since it is smaller than the sum of its proper divisors (729221089364).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661260590020 is a wasteful number, since it uses less digits than its factorization.

661260590020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43677159 (or 43677157 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 37.

The spelling of 661260590020 in words is "six hundred sixty-one billion, two hundred sixty million, five hundred ninety thousand, twenty".